Abstract: This proposal addresses two fundamental questions at the crossroads of epigenetics, stem cell biology, and regenerative medicine that relate to the chromatin-based cellular memory system. 1. Do chromatin modifications at specific genetic loci predict the progressive "restriction" of differentiation potential that occurs in neural stem cells during brain development and into adulthood? 2. Can cellular memory systems be partially "erased" or "reset" at the chromatin level in precursor cell populations to broaden their developmental potential? These studies should greatly advance our understanding of how precursor cells "remember" both their temporal and positional identities as well as determine whether this cellular memory system can be manipulated for novel therapeutic strategies. Three areas of impact are: Developmental Neurobiology, where results shed light on epigenetic mechanisms of neuronal and glial differentiation;Regenerative Medicine, where insight gained may suggest novel methods of cell fate specification;and Cancer Biology, where results may reveal how certain chromatin derangements can promote brain tumors. First, we propose investigating the changes in chromatin modifications that occur along a neural stem cell continuum from the embryo and into adulthood. Our proposed methods utilizing cells acutely isolated from the brain represent a significant advancement upon current cell culture based studies. To accomplish this, we must innovate new, integrative approaches for chromatin study. We will also employ novel and as of yet unproven approaches to "reset" chromatin memory of cell identity with the purpose of altering cell fate. Given that these ideas concerning the chromatin basis of cellular memory and strategic epigenetic manipulation are new and relatively untested, the level of risk in our proposal is substantially higher than in traditional investigator grants. We wish to embark on this tangent from our current studies to broaden the impact of our research and explore fundamental principles of cellular memory in stem cell biology. Public Health Relevance: Neural stem cells hold promise for the treatment of neurological disorders, and understanding the epigenetic mechanisms by which these precursors differentiate into neurons and glia may be key to unlocking their therapeutic potential. By performing research at the crossroads of epigenetics, stem cell biology, and regenerative medicine, we may develop novel methods of "engineering" cells for cell replacement strategies. Furthermore, our studies may lead to discoveries of how derangements in chromatin remodeling can lead to the development of brain tumors.